Qualitative and Quantitative Protein Changes Induced by Water Stress during Growth and Development of Some Sorghum (Sorghum bicolor (L.) Monech) Cultivars

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Huda Abdu Hassan Osman
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University of Khartoum
A field experiment was conducted for two seasons ( 2007/2008 and 2008/2009) at the Demonstration farm, Faculty of Agriculture, University of Khartoum to study the protein changes induced by water stress during growth and development of sorghum (Sorghum bicolor (L.) Moench). The design was split plot with three replicates .The main plots were assigned to the water treatments and the subplots to the cultivars. Water stress was induced by watering treatments at intervals of 7 (W1), 14 (W2) and 21 (W3) days, and the sorghum cultivars Wad Ahmed, Arfa Gadmak, Tabbat, Abu sabien and White Mugud . Leaves were collected for protein analysis : Total crude protein percentage and change in protein expression. They were collected at different growth stages (seedling, panicle initiation, booting, flowering, milk, soft dough, hard dough and physiological maturity) for total protein percentage, while at flowering and physiological maturity stages for change in protein expression. The results revealed that the cultivars differed significantly in their response to the level of water stress, which significantly reduced plant height in both seasons. Mean leaf area was only significantly reduced in the second season. No significant effects were registered among the number of leaves, stem diameter and days to 50% flowering. Water stress significantly increased mean seed number in the first season and had no significant effect in the second season. Mean seed number was 133.9, 194.9 and 253.3 under W1, W2 and IV W3, respectively, in the first season and 158.2, 197.4 and 180.8 in the second season. Seed weight was not significant affected by water stress during both seasons. Grain yield was significantly reduced by the long irrigation interval. Significant differences were detected between the cultivars, under stress and non stress, conditions in leaf area, number of leaves, stem diameter, during both seasons; and in seed number under stress conditions in both seasons. All cultivars, except White Mugud, exhibited yield stability under stress in the first season, while only Wad Ahmed and Arfa Gadamak had shown that stability in both seasons. The results showed differences in TCP percentage among the cultivars were detected. Water stress caused significant differences in TCP percentage in all growth stages except the booting stage in the second season, while it did nor significantly affect all growth stages except hard dough and physiological maturity stages in the first season. The TCP percentage gradually decreased towards booting and flowering stages in most cultivars and they produced a high TCP percentage under the long watering interval (21days) . As a result of water stress, different types of protein, mainly with low molecular weight (ranging from 14-117 KDa), were induced in all studied cultivars. Also, degradation of proteins (ranging from 44-77KDa) occurred in some cultivars as a response of water stress. Wad Ahmed showed a large number of induced proteins at flowering and White Mugud and Tabbat at physiological maturity compared to other cultivars. Stress proteins seemed to have contributed to yield stability under stress in Wad Ahmed and Afra Gadamak
A thesis submitted to the University of Khartoum in fulfillment of the requirements for the degree of Doctor of philosophy (Ph.D) (Molecular Plant Phsiology)
Sorghum Sorghum bicolor (L.) Monech water stress protein change Molecular Plant Phsiology Botany and Agricultural Biotechnology University of Khartoum
Huda Abdu Hassan Osman, Qualitative and Quantitative Protein Changes Induced by Water Stress during Growth and Development of Some Sorghum(Sorghum bicolor (L.) Monech) Cultivarss. – Khartoum : University of Khartoum, 2011. - 162 P. : illus., 28 cm., Ph.D.